Air-gap manifold

ABSTRACT

An air-gap manifold for the connection of exhaust gas outlet openings of an internal combustion engine, in particular of a motor vehicle engine, to an exhaust gas intake opening of an exhaust gas system, having an interior part with a plurality of exhaust gas guides plugged into one another with a sliding fit, an exterior part surrounding the interior part and made gas-tight and an air-gap present between the interior part and the exterior part, wherein at least some of the exhaust gas guides of the interior part are formed by shells which are connected to one another by common reshaping at the rim, in particular by folding, in order to reduce the manufacturing costs.

The present invention relates to an air-gap manifold for the connectionof exhaust gas outlet openings of an internal combustion engine, inparticular of a motor vehicle engine, to an exhaust gas intake openingof an exhaust gas system, having an interior part with a plurality ofexhaust gas guides plugged into one another with a sliding fit, anexterior part surrounding the interior part and made gas-tight and anair-gap present between the interior part and the exterior part.

There are various possibilities of manufacturing such air-gap manifolds.Pipe bends are customary, with the pipes being able to be manufacturedwith particularly high accuracy by internal high pressure shaping. Suchmanufacturing processes are, however, comparatively cost-intensive. Onthe other hand, it is necessary for the manifolds to be made absolutelygas-tight outwardly in order to observe the emission regulations whichare becoming more and more strict.

It is the underlying object of the invention to provide an air-gapmanifold of the initially named kind which is favorable in manufacture,on the one hand, and permits the observation of the emissionregulations, on the other hand.

This object is satisfied in that at least some of the exhaust gas guidesof the interior part are formed by shells which are connected to oneanother by common reshaping at the rim, in particular by folding,.

The design of the exhaust gas guides of the interior part from shells isparticularly cost-favorable in manufacture. On the one hand, the shellscan be drawn cost-favorably. On the other hand, the connection of theshells by common reshaping at the rim, in particular by folding, isparticularly favorable in manufacture. A large cost advantage resultsabove all with respect to weld connections in particular when productionfree of weld splashes is necessary for exhaust manifolds forturbochargers. Only expensive laser and inert arc welding techniques canthen be considered. The reshaping connection of the shells in accordancewith the invention can be carried out free of weld splashes, on the onehand, and with a low effort, on the other hand. The leak tightness ofthe reshaped connection between the shells is sufficient since theexterior shell of the manifold is absolutely gas tight and a lownon-tightness of the interior part therefore does not result inproblems.

A further cost saving results if the exterior part also consists ofshells. The exterior part can then also be manufactured comparativelycost-favorably. The assembly of the manifold is moreover simplified.

In particular sheet metal can be considered as the material for theshells of the interior part and/or of the exterior part. The metal sheetthickness of the interior part can be kept comparatively low since, incontrast to welding, no minimum thickness is required for the reshapedconnection of the shells. Different types of steel, for example alsoaustenitic steel, can thereby be used.

In order to ensure sufficient stiffness of the exhaust gas guidesdespite the thin material thickness, the shells of the interior part canbe provided with beads. The shells of the exterior part can also havebeads to increase the stiffness.

The shells of the exterior part are preferably welded to one another. Ahigh leak tightness can thus be ensured. The weld connections can bearranged at the outside so that there is no risk of contamination of theinterior of the exhaust manifold. More cost favorable welding processescan thereby also be used.

To prevent a displacement of the shells of the interior part in use, theinterior shells can be latched to one another by individual spot welds.Since only individual spot welds are required to reliably preventdisplacement, simple spot welding positions can be used for this withoutcausing the costs to increase excessively. Alternatively oradditionally, the shells can be molded jointly.

The exterior part preferably consists of two half-shells. The exhaustgas guides preferably likewise each consist of two half-shells. Aparticularly favorable manufacture and assembly is thus possible. It hasalso been found to be advantageous to arrange the separation planes ofthe interior shells and of the exterior shell approximately at rightangles to one another.

A particularly advantageous use of the air- gap embodiment in accordancewith the invention is provided in internal combustion engines withturbocharges, since the manifold in accordance with the invention can beproduced particularly cost favorably free of weld splashes.

The manufacture of an air gap manifold in accordance with the inventionpreferably takes place such that the shells of the interior part eachforming one part of the exhaust gas guides are first plugged into oneanother in accordance with the desired sliding fit arrangement, theshells each forming the other part of the exhaust gas guides are thenlikewise plugged into one another in accordance with the desired slidingfit arrangement and such that only then are the associated shells of theexhaust gas guides jointly connected to one another in that they arereshaped at the rim in pairs, in particular folded.

In accordance with the invention, it is not the individual exhaust gasguides which are first assembled from, for example, two shells each,with the exhaust gas guides formed in this manner being plugged into oneanother, but rather the plugging into one another takes place separatelyfor each half of the interior part and only then are the two halves ofall exhaust gas guides of the interior part simultaneously connected toone another. It can be ensured in this manner that the cross-sections ofthe exhaust gas guides are matched to one another in the sliding fitregions. No problems thereby occur on the joining together of theexhaust gas guides and a problem-free displacement of the individualexhaust gas guides with respect to one another can also be ensured inoperation.

After the connection of all shells plugged into one another by commonreshaping at the rim, in particular by folding, the shells of therespective exhaust gas guides are, where necessary, latched to oneanother by spot welds. The interior part is then inserted into theshells of the exterior part and these are connected to one another in agas tight manner by welding.

The shells of the interior part are preferably made of sheet metal, inparticular by deep drawing. Beads are preferably molded in to increasethe stiffness of the shells. Two half-shells per exhaust gas guide arein particular produced and are then connected to one anothersimultaneously with the other half-shells.

A non-restricting embodiment of the invention is represented in thedrawing and will be described in the following. There are shown,schematically in each case,

FIG. 1 a plan view of an air gap manifold in accordance with theinvention with a removed upper exterior shell;

FIG. 2 a section through the air gap manifold of FIG. 1 in accordancewith the line A-A,

FIG. 3 a section through the air gap manifold in accordance with theinvention in accordance with the line C-C in FIG. 2; and

FIG. 4 the detail B of FIG. 3 in an enlarged representation.

The air gap manifold shown includes an interior part 1 having aplurality of exhaust gas guides 2, 3, and 4 plugged into one anotherwith a sliding fit and an exterior part 5 surrounding the interior part1 at a spacing and made in a gas tight manner. An air gap 6 is therebyformed between the interior part 1 and the exterior part 5 and effects aheat insulation of the exhaust manifold.

The exhaust gas guides 2, 3 and 4 are each made of two half-shells 2 aand 2 b, 3 a and 3 b, 4 a and 4 b which are connected to one another atthe rim side. The connection is a fold connection such as is shown inFIG. 4. The rim of the one half-shell 3 a is bent around the rim of theother half-shell 3 b for this. Subsequently, the fold 7 is positionedobliquely, as is shown by a chain-dotted line, to increase the strengthof the connection.

The exhaust gas guides 2, 3 and 4 are, as stated, plugged into oneanother with a sliding fit. For this purpose, the fold 7 ends at arespective end 2′, 3′ of the exhaust gas guides 2 and 3 in front of theend of the respective exhaust gas guide 2, 3. A fold-free region 8 isthereby formed on which the associated end 3″, 4″ of the respectiveadjacent exhaust gas guide 2, 3 and 4 is arranged with sliding fit.

The other end 2″ of the exhaust gas guide 2 together with the exteriorshell 5 is connected in a gas tight manner to a first intake flange 9. Asecond intake flange 10 is connected in a gas tight manner to theexterior shell 5 and to the end 11′ of a side branch 11 of the exhaustgas guide 3. Finally, third and fourth intake flanges 12, 13 areconnected in a gas tight manner to the exterior shell 5 and to one rigidsleeve 14, 14′ each. The sleeve 14 sits with a sliding fit in a sidebranch 15 of the exhaust gas guide 4 and the sleeve 14′ likewise with asliding fit in the second end 4′ of the exhaust gas guide 4.

The exhaust gas guide 4 has a second branch 16 into which a furthersleeve 17 is inserted with a sliding fit. This sleeve 17 together withthe exterior part 5 is connected in a gas tight manner to an outletflange 18. A continuing pipe of a customary exhaust gas system can beconnected to the outlet flange 18. The intake flanges 9, 10, 12 and 13can correspondingly be connected to exhaust gas outlet openings of aninternal combustion engine.

The exterior part 5 likewise has two half-shells 5 a, 5 b. Theseparation plane I of the half shells 5 a and 5 b, however, extends atan angle of approximately 90° to the separation plane II of thehalf-shells 2 a, 2 b, 3 a, 3 b, 4 a and 4 b of the interior part 1 andapproximately parallel to the plane of the flanges 9, 10, 12 and 13.

The manufacture of the air-gap manifold shown substantially takes placesuch that first all half-shells 2 a, 2 b, 3 a, 3 b, 4 a and 4 b of theinterior part 1 and 5 a and 5 b of the exterior part 5 are manufactured.Beads 19 can be introduced into the half-shells in this process. Thenthe respective one half-shells 2 a, 3 a and 4 a of the interior part 1are plugged into one another in accordance with the desired siding fitarrangement. The half-shells 2 b, 3 b and 4 b of the interior part 1 arecorrespondingly plugged into one another. After the insertion of thesleeves 14 and 14′, the half shells plugged into one another 2 a, 3 aand 4 a as well as 2 b, 3 b and 4 b are inserted into a reshaping tool.Then, all half-shells 2 a, 2 b, 3 a, 3 b and 4 a, 4 b associated withone another are connected to one another by folding at the rim side. Ifnecessary, the half-shells 2 a, 2 b, 3 a, 3 b, 4 a and 4 b of theinterior part 1 are each latched to one another by individual spotwelds. A laser or MAG welding technique is used in this process in orderto avoid damaging weld splashes.

The interior part is thus complete and is inserted into the lower shell5 b of the exterior part 5 after removal from the reshaping tool. Theinterior part 1 is then connected, in particular welded, together withthis, in a gas tight manner to the intake flanges 9, 10, 12 and 13. Thesleeve 17 is then welded in a gas tight manner together with the uppershell 5 a of the exterior part 5 to the outlet flange 18. The uppershell 5 a of the exterior part 5 is subsequently placed onto the lowershell 5 b and is welded in a gas tight manner in the overlapping region.The two half-shells 5 a, 5 b of the exterior part 5 can be connected toone another by normal welding methods since the weld seam is at theoutside.

Sliding fit connections can be established between the exhaust gasguides 2, 3 and 4 by the manufacturing method described and can have avery tight fit despite the construction of the exhaust gas guides 2, 3and 4 from half-shells. Since the exhaust gas guides 2, 3 and 4 do nothave to be plugged into one another in the folded state, no problemsalso occur due to uneven roundings or cross-sections of the ends 2′, 3″and 3′, 4″ of the exhaust gas guides 2, 3 and 4 associated with oneanother.

The design of the interior part with sliding fits shown and described inanother respect permits in a known manner a substantially unimpededthermal expansion of the exhaust gas guides 2, 3 and 4 of the interiorpart 1, in particular a larger thermal expansion due to the greaterheating of the interior part 1 with respect to the exterior part 5. Theexterior part 5, on the other hand, ensures a high gas tightness of theair-gap manifold. In this manner, a properly suitable air-gap manifoldcan be manufactured at comparatively very low costs.

Reference Numeral List

-   1 interior part-   2 exhaust gas guide-   2′ end of 2-   2″ end of 2-   2 a half-shell-   2 a half-shell-   3 exhaust gas guide-   3′ end of 3-   3″ end of 3-   3 a half-shell-   3 a half-shell-   4 exhaust gas guide-   4′ end of 4-   4″ end of 4-   4 a half-shell-   4 a half-shell-   5 exterior part-   5 a half-shell-   5 a half-shell-   6 air gap-   7 fold-   8 fold-free region-   9 intake flange-   10 intake flange-   11 branch of 3-   11′ end of 11-   12 intake flange-   13 intake flange-   14, 14′ sleeve-   15 branch of 4-   16 branch of 4-   17 sleeve-   18 outlet flange-   19 bead-   I separation plane-   II separation plane

1. An air-gap manifold for the connection of exhaust gas outlet openingsof an internal combustion engine, in particular of a motor vehicleengine, to an exhaust gas intake opening of an exhaust gas system,having an interior part (1) with a plurality of exhaust gas guides (2,3, 4) plugged into one another with a sliding fit, an exterior part (5)surrounding the inner part (1) and made gas-tight and an air-gap (6)present between the interior part (1) and the exterior part (5),characterized in that at least some of the exhaust gas guides (2, 3, 4)of the interior part (1) are formed by shells (2 a, 2 b, 3 a, 3 b, 4 a,4 b) which are connected to one another by common reshaping at the rim,in particular by folding.
 2. An air-gap manifold in accordance withclaim 1, characterized in that the exterior part (5) likewise consistsof shells (5 a, 5 b).
 3. An air-gap manifold in accordance with claim 1,characterized in that the shells (2 a, 2 b, 3 a, 3 b, 4 a, 4 b) of theinterior part (1) and/or the shells (5 a, 5 b) of the exterior part (5)consist of sheet metal.
 4. An air-gap manifold in accordance with claim1, characterized in that the shells (2 a, 2 b, 3 a, 3 b, 4 a, 4 b) ofthe interior part (1) and/or the shells (5 a, 5 b) of the exterior part(5) have beads (19).
 5. An air-gap manifold in accordance with claim 3,characterized in that the shells (5 a, 5 b) of the exterior part (5) arewelded to one another.
 6. An air-gap manifold in accordance with claim1, characterized in that the shells (2 a, 2 b, 3 a, 3 b, 4 a, 4 b) ofthe interior part are latched to one another, in particular byindividual spot welds.
 7. An air-gap manifold in accordance with claim1, characterized in that the exterior part (5) consists of twohalf-shells (5 a, 5 b).
 8. An air-gap manifold in accordance with claim1, characterized in that the shells (2 a, 2 b, 3 a, 3 b, 4 a, 4 b) ofthe interior part (1) are half-shells.
 9. An air-gap manifold inaccordance with claim 8, characterized in that the separation plane (I)of the exterior shell (5) and the separation plane (II) of the interiorshell (1) stand approximately at right angles to one another.
 10. Anair-gap manifold in accordance with claim 1, characterized by the usefor an internal combustion engine with a turbocharger.
 11. A method forthe manufacture of an air-gap manifold for the connection of exhaust gasoutlet openings of an internal combustion engine, in particular of amotor vehicle engine, to an exhaust gas intake opening of an exhaust gassystem, the air gap manifold having an interior terior part (1) with aplurality of exhaust gas guides (2, 3, 4) plugged into one another witha sliding fit, an exterior part (5) surrounding the inner part (1) andmade gas-tight and an air-gap (6) present between the interior part (1)and the exterior part (5), wherein at least some of the exhaust gasguides (2, 3, 4) of the interior part (1) are formed by shells (2 a, 2b, 3 a, 3 b, 4 a, 4 b) which are connected to one another by commonreshaping at the rim, in particular by folding. characterized in thatthe shells (2 a, 3 a, 4 a) of the interior part (1) each forming onepart of the exhaust gas guides (2, 3, 4) are first plugged into oneanother in accordance with the desired sliding fit arrangement, theshells (2 b, 3 b, 4 b) each forming the other part of the exhaust gasguides (2, 3, 4) are then likewise plugged into one another inaccordance with the desired sliding fit arrangement; and in that onlythen are the associated shells (2 a, 2 b, 3 a, 3 b, 4 a, 4 b) of theexhaust gas guides (2, 3, 4) jointly connected to one another in thatthey are reshaped at the rim in pairs, in particular folded.
 12. Amethod in accordance with claim 11, characterized in that the shells (2a, 2 b, 3 a, 3 b, 4 a, 4 b) of the interior part (1) are latched to oneanother by individual spot welds.
 13. A method in accordance with claim11, characterized in that the shells (5 a, 5 b) of the exterior part (5)are welded to one another in a gas tight manner.
 14. A method inaccordance with claim 11, characterized in that the shells (2 a, 2 b, 3a, 3 b, 4 a, 4 b) of the interior part (1) and/or the shells (5 a, 5 b)of the exterior part (5) consist of sheet metal.
 15. A method inaccordance with claim 11, characterized in that the shells (2 a, 2 b, 3a, 3 b, 4 a, 4 b) of the interior part (1) and/or the shells (5 a, 5 b)of the exterior part (5) are provided with beads.